DEVELOPMENT OF A PARTIALLY THREE-DIMENSIONAL MODEL FOR SHIP MOTION IN A HARBOR WITH ARBITRARY BATHYMETRY

Takumi Ohyama, Mitsuru Tsuchida

Abstract

A numerical method has been developed for the analysis of ship motions in a harbor with arbitrary bathymetry. A BEM-based 3-D model, applied partially to a near-field surrounding a ship, is combined with a FEM-based 2-D model, utilized in the remainder of harbor domain. This combination may achieve an efficient computation of the ship motions with taking into account of wave deformation in a harbor. Preliminary examinations have been performed to investigate appropriate location of a matching boundary where these two models are coupled. It is found that, for reliable prediction, (2 ~ 3)ft (h: water depth) is required for the distance between the matching boundary and a body. The numerical results of added mass and damping coefficients for a rectangular floating body in a rectangular basin are then compared with those obtained from a conventional numerical model. Favorable agreement between the results verifies the present numerical method. Ship motions in a harbor with slowly varying depth are also demonstrated.